Selected QuikSCAT Ice Extent Products are now available. Additional
products will be posted as they are available. We note that a Near-Real-Time
(NRT) version of the algorithm is run on QuikSCAT data as part of
the wind processing to mask out sea ice regions.

The QuikSCAT sea ice extent algorithm is based on an modification
of the NSCAT algorithm. The estimated extent of sea ice is estimated
for each Ant and Arc regional image for both slices and eggs. The
polarization ratio (AV-AH in dB), incidence angle dependence
(B images), and the sigma-0 estimate error standard deviation
(V images) are used to perform the sea ice/ocean discrimination.
Residual misclassification noise is reduced using binary image processing
techniques such as region growing, erosion, and dilation resulting
in a low pass filtered version of the sea ice extent edge. The resulting
edge closely matches the NSIDC SSM/I-derived 30% ice concentration
edge.

The sea ice extent product is in two forms: a masked image generated
by applying the binary extent mask to the V-pol, A-image
(.imsk file) and an ASCII edge file (.ie file). The lat/lon values
in the ASCII edge files were obtained by computing the lat/lon location
of each pixel along the edge of the binary ice mask. Ice extent
products are included in the V-pol, ascending/descending, A
image directories of the Antarctic (Ant) and Arctic (Arc) regions
for eggs (quev) and slices (qusv).

Masked V-pol files (.imsk): Masked
V-pol, A image of quev and qusv images of Antarctica (Ant)
and the(Arc). Ocean areas outside of the estimated sea ice extent
are set to the no-data value.

IE files (.ie): ASCII files containing
latitude/longitude pairs which represent the contour points of the
estimated sea ice edge. Each line entry in the file consists of
two values: a longitude and a lattitude. The longitude values range
from -180 to +180. Multiple contours are separated by a '0 0' entry.